Date: Thu, 11 Jul 2013 15:30:40 +0200 From: Lars Engels <lme@FreeBSD.org> To: asomers@gmail.com Cc: hackers@freebsd.org, Julian Elischer <julian@elischer.org>, Jordan Hubbard <jkh@mail.turbofuzz.com> Subject: Re: Kernel dumps [was Re: possible changes from Panzura] Message-ID: <20130711133040.GO88288@e-new.0x20.net> In-Reply-To: <CAOtMX2hLvYnQsZnCn9hC8GjukBy4ad=48yLpqJfuT_7Utq2vEA@mail.gmail.com> References: <FDEEB55D-823B-4899-8EEC-7F5306D91F5B@elischer.org> <9890DFF1-892A-4DCA-9E33-B70681154F43@mail.turbofuzz.com> <CAOtMX2hLvYnQsZnCn9hC8GjukBy4ad=48yLpqJfuT_7Utq2vEA@mail.gmail.com>
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--SDZNRjzUoAX9KAL/ Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 10, 2013 at 02:04:17PM -0600, asomers@gmail.com wrote: > On Wed, Jul 10, 2013 at 12:57 PM, Jordan Hubbard <jkh@mail.turbofuzz.com>= wrote: > > > > On Jul 10, 2013, at 11:16 AM, Julian Elischer <julian@elischer.org> wro= te: > > > >> My first candidates are: > > > > Those sound useful. Just out of curiosity, however, since we're on > > the topic of kernel dumps: Has anyone even looked into the notion > > of an emergency fall-back network stack to enable remote kernel > > panic (or system hang) debugging, the way OS X lets you do? I can't > > tell you the number of times I've NMI'd a Mac and connected to it > > remotely in a scenario where everything was totally wedged and just > > a couple of minutes in kgdb (or now lldb) quickly showed that > > everything was waiting on a specific lock and the problem became > > manifestly clear. > > > > The feature also lets you scrape a panic'd machine with automation, > > running some kgdb scripts against it to glean useful information for > > later analysis vs having to have someone schlep the dump image > > manually to triage. It's going to be damn hard to live without this > > now, and if someone else isn't working on it, that's good to know > > too! >=20 > I don't doubt that it would be useful to have an emergency network > stack. But have you ever looked into debugging over firewire? We've > had success with it. All of our development machines are connected to > a single firewire bus. When one panics, we can remotely debug it with > both kdb and ddb. It's not ethernet , but it's still much faster than > a serial port. > https://wiki.freebsd.org/DebugWithDcons Debugging over Firewire may be very nice to use, but Firewire is dead while every single device nowadays has a network interface, admittedly it's often wireless. --SDZNRjzUoAX9KAL/ Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (FreeBSD) iEYEARECAAYFAlHes4AACgkQKc512sD3afg29QCdGEG7bQhxyoI6W8TyyOYvg0Wx 0HcAnj3R3pX1GLuO6zZW3XmLQVQOO5G9 =olYf -----END PGP SIGNATURE----- --SDZNRjzUoAX9KAL/--
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